广西北部湾钝缀锦蛤精巢发育、精子发生及超微结构研究

Testis and germ cell development and sperm ultrastructure of Tapes conspersus inhabiting the Beibu Gulf,Guangxi,China

为了解广西北部湾海域钝缀锦蛤(Tapes conspersus)精巢周年发育情况、精子发生过程及成熟精子超微结构,本文采用组织切片、扫描电镜、透射电镜技术对钝缀锦蛤精巢发育过程、精子的发生及超微结构进行了研究。研究结果显示:目前广西北部湾钝缀锦蛤未见雌雄同体情况,观察的个体皆为雌雄异体。一周年的采样结果中,雌性个体138个、雄性个体102个,雌雄的性比约为1.35︰1。1年即为精巢发育的一个周期,发育时期可以划分为增殖期、生长期、成熟期、排放期、休止期共5个主要分期。精细胞的发育可以划分为5个主要分期,即精原细胞期、初级精母细胞期、次级精母细胞期、精细胞期、成熟精子期。精子全长约59.27μm,属于鞭毛型,由头部、中部、尾部3个部分共同构成,精子头部呈圆锥型,由细胞核和顶体组成,顶体呈倒“V”型。电子在顶体的分布是不均匀的,顶体前部电子分布少,后部分布多。中部主要由两部分构成,即5个圆形排列的线粒体和一个中心粒复合体。轴丝与质膜两个部分共同构成了尾部,轴丝的双联体微管结构横切面表现为“9+2”型。此外,本实验观察到少部分精子尾部呈双尾结构。

To understand the annual testis development,spermatogenesis,and ultrastructure of the mature sperm of Tapes conspersus in the Beibu Gulf of Guangxi were studied.In this experiment,testis development,sper-matogenesis,and the ultrastructure of T.conspersus were studied using tissue section,scanning electron micro-scope,and a transmission electron microscope.Research shows that presently,no hermaphrodites exist in the Tapes conspersus in Beibu Gulf of Guangxi,and all observed individuals are dioecious.From the first anniver-sary of the sampling results,138 females and 102 males were obtained.The sex ratio between males and females is approximately 1.35︰1;one year is a cycle of testis development.The developmental period can be divided into five main stages:proliferation period,growth period,mature period,discharge period,and the resting period.The development of sperm cells can be divided into five main stages:spermatogonia,primary spermatocytes,secondary spermatocytes,spermatocytes,and mature spermatids.The total length of the sperm is approximately 59.27μm,which is of the flagella type.It is composed of three parts:head,middle,and tail.The head of the sperm is conical,composed of nucleus and acrosome,and the acrosome has an inverted“V”shape.Electron dis-tribution in the acrosome is uneven,the distribution of electrons in the front part of the acrosome is few,and the distribution in the back part is abundant.The middle part is mainly composed of two parts,five circularly ar-ranged mitochondria and a centriole complex.The two parts of the axon filament and the plasma membrane to-gether constitute the tail.The cross section of the doublet microtubule structure of the axon is shown as a“9+2”type.Additionally,few sperm tails were observed to have a double-tailed structure in this experiment.